Chalk can block the bond
Old paint can turn into a loose powder. New paint may stick to that powder instead of the wall.
Water may be trapped
Leaks, wet stucco, and fast paint after washing can trap water. The pressure can push the coating away.
The wrong primer can fail
A very chalky or porous wall may need a masonry conditioner or primer. A normal top coat may not be enough.
Cracks can let water in
Small cracks can grow or move. Paint is not a repair for a deep wall problem.
Good prep lowers the risk
Wash, dry, scrape, repair, prime when needed, and use a finish made for masonry. Each step has a reason.
What to do next
Rub the wall with a clean hand. Photograph powder, bubbles, cracks, and wet spots.